My thoughts, FWIW, I agree with MD pretty much across the board. There be a tremendous amount of chaos unleashed with the primer pops, and our job is to make the chaos as uniform as possible from shot to shot. Some things are more important than others, but if you fiddle long enough you'll figure out what matters. An example that gave me pause years ago: .338 Win load work up, Shilen DGAM action and barrel properly installed on a quality composite stock. Load 1 goes down range to the 100 yard target and groups about 3", this with an ES of 5 fps. Load #2 follows and has an ES of about 12-13 as I recall, and groups in the 3/4" range. Easy choice that was. Paper is paper, dead meat is dinner.
I like to explore the numbers, but at the end of the day don't forget what the purpose of the drill is....
